Problem: $-9kl + km + 4k - 2 = -7l + 2$ Solve for $k$.
Explanation: Combine constant terms on the right. $-9kl + km + 4k - {2} = -7l + {2}$ $-9kl + km + 4k = -7l + {4}$ Notice that all the terms on the left-hand side of the equation have $k$ in them. $-9{k}l + 1{k}m + 4{k} = -7l + 4$ Factor out the $k$ ${k} \cdot \left( -9l + m + 4 \right) = -7l + 4$ Isolate the $k$ $k \cdot \left( -{9l + m + 4} \right) = -7l + 4$ $k = \dfrac{ -7l + 4 }{ -{9l + m + 4} }$